Biodiversity is declining at an alarming rate due to increasing pressures from human activities and climate change. This urgent situation calls for comprehensive biodiversity observations that can inform policy and action for conservation and restoration, while also advancing our understanding of biodiversity’s role in ecosystem functioning and resilience. Functional diversity, encompassing the diversity of functional traits within and among species, communities and ecosystems, is a key dimension of biodiversity. It links directly to ecosystem processes and services, and can be measured at multiple scales, from individuals to landscapes, incorporating both intra- and interspecific variation. This session invites contributions that explore how and why functional traits and functional diversity are changing across spatial (from local to global) and temporal (from diurnal to decadal) scales. We welcome a wide range of approaches, including in-situ, experimental or modeling studies, and close-range, airborne, or satellite remote sensing, and combinations of these methods. We welcome contributions from various ecosystems and taxa, including, for example, plants and animals in forests, grasslands or marine ecosystems. We particularly encourage contributions that connect functional diversity to ecosystem productivity, stability, or resilience, as well as to other biodiversity dimensions such as taxonomic, phylogenetic, or genetic diversity. This session aims to foster interdisciplinary dialogue and showcase innovative, integrative research. We welcome participation from researchers across disciplines, institutions, and career stages to contribute to a better understanding of functional diversity and its critical role in sustaining life on Earth.